View: https://www.reddit.com/r/AskHistorians/comments/5njsgu/where_and_when_did_stereotypes_about_penis_size/
"The stereotype that Africans and African-Americans having larger penises is an old one. I highly recommend you check out Withrop Jordan's White over Black, in no small part because it is a neo-Freudian analysis about the origins of racism in the United States. Admittedly, he is not explicitly describing his historical discussion as Freudian, and he believes that race is a biological phenomenon, but it is still among the best books for sources on English and American ideas about race from 1550-1815.
Jordan states that there are Portuguese tales in the fifteenth century that mention African penis size, citing Andrea Bianco's 1436 map of the World among others. Descriptions of Africans in seventeenth and eighteenth century sources also make mention of Africans' penises. Frequently, the Europeans discuss penises when talking about the polygamy practiced by many African groups, whereby African men take several wives. Men like Pieter de Marees discuss the aggressive sexuality of African men, that they are territorial with their wives and their lasciviousness. De Marees described the men along the Gold Coast as:
They are also blessed with a large Male member, which they esteem highly, considering it a great privilege to be allowed to work with a great tool. Generally they are well endowed below the belt, surpassing our Dutch Nation in this respect; and being fully conscious of this, they do not spare it, but make it work, as we shall later describe at length. (1602)
Jordan continues on, and explains that by the end of the eighteenth century, ideas of Africans having larger penises was something of a commonplace idea, even among scientific circles. He states that Linnaeus himself thought that the "Negro's penis was much longer and wider." (p. 158)
EDIT: Another example of early accounts include Jobson, The Golden Trade (1623) where he stated that the Africans "were furnished with such members as are after a sort burdensome unto them."
Jordan presents a more thorough discussion of the natural philosophers late in the book. Charles White, a surgeon and amateur biologist posited that different races (which in his mind were real biological differences) were expressed physically. Africans were "brute" and overly sexual, ruled by emotion, and
the Penis of an African is larger than that of an European... has, I believe, been shewn in every anatomical school in London. Preparations of them are preserved in most anatomical museums; and I have one in mine." (1799)
Physiologists tried to test the above anecdotal evidence and the claims of enlightenment thinkers in the 1940s. Cobb, "Physical Anthropology of the American Negro" American Journal of Physical Anthropology (1942) pp. 158-159 claimed that five anatomical studies consulted indicated that "Negros" had measurably larger penises. Jordan cites other studies on pp. 159-160, and also states that social scientists argue that claims of larger penises has no basis in fact. The dispute is less about methods and results, than about racist insinuations in the myth. As White argued, claims about Africans hyper-sexuality were part of the stock and trade of racist arguments meant to protect white women, and the idea that Africans possessed larger penises was considered evidence. Black females were also considered hyper-sexual, and many of the descriptions of Africans and Afro-Caribbean slaves make special reference to their breasts (Morgan, "Some Could Suckle Over Their Shoulder" WMQ 1997.
What is further, is that male Native Americans were considered more feminine than Europeans - they could not grow beards, they were thought to be lazy, and other racist ideas were spread by Europeans encountering the Natives. Following these ideas about a lack of masculinity, was that Native Americans were hypo-sexual, and had smaller penises. I'm not aware if this myth persisted to the present, but it helps show the way Europeans perceived sexuality, and how it physically manifested itself."
